Researchers discover ancient symbiosis between animals, bacteria

Marine shallow water sandy bottoms on the surface appear desert-like and empty, but in the interstitial space between the sand grains a diverse fauna flourishes. In addition to bacteria and protozoa numerous animal phyla have been found here, some only here. One of the strangest members of this interstitial fauna is Paracatenula, a several millimeters long, mouth and gut-less flatworm, which is found from tropical oceans to the Mediterranean. These worms are the focus of a research project led by Jorg Ott at the Department of Marine Biology of the University of Vienna with funding from the Austrian Science Foundation (FWF). The surprising results of this research have now been published in the journal Proceedings of the National Academy of Sciences (PNAS).